The Angra A wreck - or Copper-fastened wreck - at Porto Novo; Angra Bay, Terceira Island, Azores, wasbriefly examined during the
general survey of the inner harbor area in 1996. This wreck lies off the northern corner of Porto Novo, beneath
approximately 5 to 7 meters of water. It is oriented along a northwest-southeast axis, but the stem and stern of
the vessel have not been identified due to the lack of endposts, deadwood timbers, or diagnostic features on the
keel. The site is characterized by an oval ballast mound measuring 35 meters in length by 11.5 meters in width;
beneath the ballast mound is an articulated lower hull structure measuring 40 meters in length by approximately
11.5 meters in breadth. The northwestern end of the wreckis lodged between two large boulders.

Hull Timbers

The wreck consists of a 40-meter length of structure from the bottom of a heavily-built wooden vessel.Ballast covers much of the
hull, but exposed timbers along the southwestern side and southeastern end of the wreck provided much information
about the construction of the ship. Identifiable timbers include the keel, thelower portions of frames
(consisting of floor timbers and futtocks), a bilge stringer, and both external plankingand internal (or 'ceiling')
planking.

The condition of the visible timbers varied: the keel, frames and planking at the southeast end of the wreckhave long been exposed to
decay and the depredations of marine wood-boring organisms such as Teredonavalis (teredo worms) and as result are in a
very poor condition; frame timbers amidships appear to have been protected by sand and ballast, and in some places
retain their original surfaces, complete with tools marks.The wreck timbers still buried
under the ballast should be in good condition. A 5.42 meter length of the ship's keel protrudes from the ballast pile at the
southeastern end of the wreck. This timber was of substantial dimensions, 38 cm moulded by 29 cm sided. The keel's
surfaces were considerably degrade, and we could not identify typical keel features such as the outer planking
rabbets, a shoe (or 'false keel'), or timber scarfs.

Southwest
end of Angra A wreck, with the ballast mound at the right
Photo: Cristoph Gerik

The wreck's frames
were, like the keel, of very substantial size, with the sided dimensions averagingbetween 23 and 28 cm and
the moulded dimension averaging about 20 cm. The frames were very closelyspaced amidships on 59 cm
centers, with an average space of 5 cm between each set of frames. The framesexhibited very low dead rise
- the angle of rise above the horizontal plane of the keel - suggesting that thevessel was nearly flat-bottomed
with a pronounced turn of the bilge, giving the hull a U-shaped section ratherthan a V-shaped section.
The minimal deadrise indicates that the hull was designed for maximum cargocapacity amidships.

The wreck's outer planking
measured 9 cm in thickness; the badly deteriorated state of the planking at the southeast end of the wreck did
not allow us to identify planking seams, and the average width of the planks is therefore unknown. The outer planking
was attached to the frames with copper-alloy spikes. We did not seeany evidence on the outer
planking or keel of any type of metallic or wooden sheathing to protect the woodfrom marine growth or teredo
worms.

Several strakes of
ceiling planking were exposed on the southwestern side of the hull, and averaged 29 cmin width by 8 cm in thickness.
A heavy timber extending along the southwest side of the wreck was identified asa bilge stringer. The stringer
was quite large, 29 cm moulded by 23 cm sided, and was
fastened to the frameswith copper-alloy bolts.

There were no visible
remains of the hull structure above the level of the bilge stringer, although it is possible that part of the vessel's
keelson may still exist beneath the ballast.

Fasteners

As noted above, the wreck contained copper-alloy fasteners in the form of spikes and bolts. We did not noteany treenails in the construction
of the frames or attachments of the planking, but the survey was limited inextent, and it is possible
that such fasteners may have been overlooked. The presence of copper fastenerspermits approximate dating
of the vessel, since spikes and bolts of this material appear to have beenuncommon in large wooden
ships prior to the nineteenth century.

The use
of copper for ship fasteners dates back to the classical era, and they appear on wrecks dating to the 5th and 4th
centuries B.C. in the form of clenched nails. By the Roman era, however, iron replaced copperr in shipbuilding , due to its greater strength and lesser
cost.

Fasteners of iron or
wood remained the standard through the medieval and early modern eras until the last quarter of the 18th century.
The appearance of copper and copper-alloy fasteners was a result of the Royal Navy's experimentation with copper
sheathing to protect the bottoms of wooden ships.

Copper sheathing was
first used in 1761 and was a great success in terms of improving sailing speed, keeping ship's bottoms free of
marine growth, and repelling teredo worms. There were drawbacks to copper: it was expensive, it wore out quickly,
and perhaps most seriously, copper sheathing over iron-fastened hulls created a galvanic reaction that quickly
destroyed iron.

By 1783 the Royal Navy
learned to build its warships with copper spikes and bolts below the waterline, which greatly relieved the problem
of galvanic corrosion.

A copper-alloy
fastener from Angra A

Photo: Cristoph Gerik

From the 1780's to
the 1830's copper-fastened and sheathed vessels became more common, particularlyfor naval vessels and larger
merchant craft, but the great expense and short life span of pure copper plateswere still a problem and
kept this type of sheathing from being widely adapted. The problems were finally overcome in 1832, when George
F. Muntz of England patented 'yellow metal' or 'Muntz metal', an alloy of 60% copper and 40% zinc, that was hot-rolled
into thin sheathing plates. Muntz's alloy was flexible enough to adapt itself to a wooden hull, corroded at a much
slower rate than copper, and because of the high percentage of inexpensive zinc cost substantially less than pure
copper. Muntz aggressively marketed his new alloy duringthe 1830's, and it began
to see widespread use by the 1840's.

Discussion

The copper-fastened wreck in Porto Novo, Angra bay, represents the bottom of a relatively large woodenvessel. The ends of the vessel
could not be determined during the survey due to the lack of a stem or sternpostor their related structures;
the low angle of deadrise of the frames suggests that the vessel was quite boxy amidships, and it was most likely
a cargo-carrying vessel. The presence of copper fasteners on the wreck inPorto Novo tells us that
the hull was built sometime after 1783, very likely dates to the 19th century, and most probably was built after
1840. While no copper-alloy sheathing was noted on the wreck, we can assume that itwas probably sheathed during
its career.

Further investigation
of the wreck's construction and of artifacts located in the ballast or between framesmight permit closer dating
of the wreck. The percentage of copper and other metals in the fasteners could alsobe tested to see if the fasteners
conform to Muntz's 1832 patent specifications.